The invention relates to a mold for manufacturing concrete moldings by machine, having a bottom mold part with at least one mold chamber and having a top mold part with a load plate, and there being as many dies as mold chambers.
Filling of the bottom mold parts of such molds in the production machine takes place by means of a so-called filling carriage. This is a flat hopper which contains the molding material and is moved back and forth directly above the top edges of the mold chambers. The material thus drops into the chambers and is scraped up flush by the border of the filling carriage as the latter makes its return movement. However, the concrete, which is only pourable to a limited extent, is usually distributed unevenly in the filling carriage and, depending on the position of the individual chambers within the mold and/or depending on the size of the mold-chamber surface area, different traversing times which are available for the molding material to be lowered into the chambers are necessarily produced. Uniform filling of the mold chambers is thus problematic.
However, if the individual mold chambers are filled with different quantities or if, in the case of a large-surface-area mold chamber, the concrete filling is distributed unevenly therein, this produces moldings of at least locally differing densities and/or heights, depending on the extent to which the top mold part remains parallel to the mold table during compaction. In the case of elongate molds, despite all efforts being made in design terms, this cannot always be ensured to the desired extent.
It is indeed already known, from DE 24 06 688 A1, to actuate the dies of multichamber molds by means of individual hydraulic cylinders which are activated by the same pressure source in order, in view of non-uniform filling of the mold, at least to carry out compaction uniformly and consequently to avoid differences in strength of the individual moldings. Nevertheless, differing heights have to be accepted here, although, for some products, this is not really disadvantageous.